Flotation of minerals



UNITED STATES PATENT OFFICE.'

CLEMENT L. PERKINS, 0F PITTSBURGH, PENNSYLVANIA. ASSIGNOR TO METALS RECOVERY COMPANY, OF NEW YORK, N. Y., A CORPORATION OF MAINE.

FLOTATION OF MINERALS.

No Drawing.

To all whom i may concern Be it known that I, CLEMENT L. PERKINS, a citizen of the United States, residing at Pittsburgh, in the county of Allegheny, State of Pennsylvania, have invented certainnew and useful Improvements in Flotation of Minerals; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable othersskilled in the art to which it appertains to make and use the same.

his invention relates to the concentration of minerals, such as sulfid ores and the like, by flotation, and is based upon the discovery that improved results can be obtained by carrying out the flotation operation with the addition, to the ore or mineral pulp, of certain non-oleaginous solid organic compounds, which themselves have substantially no frothing properties, but which have valuable properties as collecting agents for the mineral. Such collecting agents, although substantially non-frothing,

nevertheless so act upon the minerals that they very materially assist in the recovery of the minerals when used in connection with a suitable frothing agent.

Among the agents which are of particular value as collecting agents, and which are substantially non-frothing, are reduced compounds which are relatively easily oxidizable, such as, for example, diazo-aminobenzene. It may be that these compounds are adsorbed at the surface of the sulfid or mineral particles, and that they so modify the sulfid or mineral surfaces that these surfaces are less easily wet by water or made more readily susceptible to attachment by the air bubbles. In some cases the reduced compound is apparently further reduced by the action of the sulfid particles, so that the action may partake of both a chemical and physical nature. These agents also appear to be adsorbed to some extent by certain of the gangue particles, but in this case oxidation of the collecting agent apparently takes place at the surface of the gangue particles, so that the actual surface resented is an oxidizing or oxidized sur ace,

Specification of Letters Patent.

Patented J anAc, 1921,

Application filed July 21, 1919. Serial No. 312,247.

while in the case of the sulfid particles it appears to be a reduced surface. However, I do not desire to limit myself b any theoretlcal explanation of the mec anism of the action of these collecting agents.

Although the collecting agents are substantlally insoluble, and are commonly referred to as insoluble, nevertheless, they are soluble to a very small degree, and it appears to be by reason of this solubility that they are able to act upon the minerals and exert their marked selective and collecting properties.

These collecting agents are, as above noted, non-frothing, and it is, therefore,

important to supplement their action by an agent which will provide an appropriate amount of froth. The frothing agent, however, may be entirely inadequate to perform the flotation process by itself, inasmuch as its function appears to be simply to provide bubbles in suflicient quantity and of sufficient persistency to overflow into the launder of the flotation machine, thereby mechanieally facilitating the removal of the mineral concentrate.

Among the collecting agents of the character above referredto, that is, which are substantially non-frothing, are included certain of the aromatic thio-ureas, and many of the azo and diazo compounds. A collecting agent which I have found of particular value is diazo-amino -benzene,

The collecting agents can be incorporated with the ore or mineral pulp in any suitable manner which will insure their uniform incorporation and dissemination throughout the pulp. They may thus be incorporated by grinding in the tube mill in which the ore itself is ground, or they may be dissolved in an organic solvent therefor, and the resulting solution added to the ore pulp. When a solvent of the collecting agent is employed, it may advantageously itself be an agent with good frothing properties, so that its action will supplement the collecting action of the collecting agent. After agitation.

the collecting agent and a suitable frothing agent have been thoroughly and uniformly.

a flotation operation, as in an ordinary Callow cell, or in apparatus where the air is incorporated in the ore pulp by mechanlcal It is of advantage in many cases to add to the ore pulp a small amount of alkali, which may be suflicient in amount to give to the ore pulp a distinct alkaline reaction. When alkalis are used, it is desirable to give them an appreciable time of contact with the ore pulp before subjecting the latter to flotation. When posslble, it appears preferable to add the alkalis 1n the grinding mill, so that they w1ll be present during the grinding operation. The alkali may be caustic alkali, such as sodium hydrate, or an alkaline salt, such as sodium carbonate, or even lime or calcium oxid or hydrate can be used.

The amount of the collecting agent added may vary somewhat, and may be as little as one-fifth or one-fourth of a pound per ton of ore (that is, calculated on the weight of the ore and not of the ore pulp). I have obtained good results with the use of as little as one-thirtieth of a pound per ton of ore. Larger amounts may, however, be used.

The invention will be further illustrated by the following specific examples of tests made upon a copper sulfid ore having a silicious gangue containing its floatable or sulfid copper in the form of a mixture of chalcocite and chalcopyrite, that is, so-callcd porphyry ores, such as those of the Utah Copper Company. In general, treatment of the ore with alkalis, as above noted, gives improved results, the alkalis themselves apparently having a valuable effect upon the ores in improving the floatation thereof.

1. Diazo-amiao-benzene and terpineol.- 500 parts by weight of Utah Copper Companys ore was ground in the pebble mill with 250 parts of water, sodium hydroxid equivalent to two pounds per ton of dry ore, and diazo-amino-benzene equivalent to one-fifth pound per ton. The ground pulp was transferred to a Callow rougher cell, diluted, and floated with the addition of terpineol equivalent to about one-tenth pound per ton. The heads for this test contained 1.42 per cent. copper, the concentrates produced contained about 22.4 per cent. copper, and the recovery was about 91.4 per cent. a

2. Dia-zo-omnino-beneene and terpineol. The details of the test were the same as those of No. 1, except that the proportion of diazo-amino-benzene was reduced to onethirtieth pound per ton. The heads for test No. 2 contained 1.38 per cent. copper,

the concentrate produced contained about 17.3 per cent. copper, and therecovery was about 87.7 per cent.

3. Dimeoamino-benzene and pine oil.- The details of this test were the same as those of No. 1, except that steam-distilled pine oil was substituted for terpineol. The roportion of pine oil used was about oneourth pound per ton of dry ore. The

heads for test No. 3 contained 1.39 per cent.

copper, the concentrates produced contained about 17.9 per cent. copper, and the recovery was about 88.6 per cent.

4. Diaeo-amino-benzene dissolved in myhams-Five hundred parts by weight of Utah Copper Companys ore were ground with 250 parts of water and sodium hydroxid equivalent to two pounds per ton of dry ore. The ground ore pulp was diluted, and to the ground and diluted pulp was then added a solution of diazo-aminobenzene in xylidin. The proportion of the compound reagent used was one-half pound per. ton of dry ore. It contained about 80 per cent. xylidin and 20 per cent. diazoamino-benzene. The pulp was transferred immediately to a (allow rougher cell and floated. The heads for this test contained 1.39 per cent. copper, the concentrates contained about 21.9 per cent. copper, and the recovery was about 91.2 per cent.

As appears from these examples, difl'erent frothing agents may be used, and the collecting agents may be itself dissolved in a solvent which has good frothing qualities. Xylidin is a good example of a valuable'floatation agent which serves as a solvent for the diazo-amino-benzene and supplies the necessary froth for the flotation operation. Among other solvents may be mentioned anilin, dimethyl anilin, toluidin and other organic liquids in which the particular collecting agent is soluble, such as cresol, alcohol, etc. The solution of diazoamino-benzene in xylidin can be promoted by heating, but prolonged heating may result in chemical changes which reduces the effectiveness of the resulting product. i

The collecting agent can with advantage be used in addition to many of the usual oil mixtures which are commonly employed in flotation, with resulting improvements in the flotation operation. Flotation oils or oil mixtures which are good frothing agents, such as pine oil and other wood distillation oils, are of particular value, inasmuch as they supplement the action of the collecting agent, and are themselves supplemented in their ore floating properties by the collecting action of the collecting agent.

In the flotation of zinc-lead ores, it has been found of advantage to grind the collecting agent with the neutral ore pulp; and still better results have been obtained when copper sulfate and sulfuric acid were also used in the proportion of about one pound of each per ton of dry ore. A small amount of a suitable frothing agent, as above noted, should also be used.

It is characteristic of the invention that the froth obtained is readily broken up, while a relatively clean concentrate and high recovery can, nevertheless, be obtained. A' art of the collecting agent, together wit a part of the frothing agent, can sometimes be recovered so that they are available for use in the treatment of further amounts of ore; for example, by recovering the circuit water from the concentrates, or even that from the tailings, and returning the same to the process, with resulting economy in the amount to be added for subsequent operations. The amount of the collecting agent can, however, in many cases be reduced to such a small amount that it is feasible to practise the invention without such recovery of the agents employed.

As above noted, the action of the collect inn agent appears to be a selective action upon the mineral surfaces, rather than any action of importance upon the water itself, inasmuch as the removal of all water from the ore pulp, after the collecting agent has been incorporated therewith, and the subsequent washing of the ore, does not deprive it of its improved flotation properties when made into an ore pulp with fresh water and subjected to flotation. Investigations of this kind indicate that the collecting agents have a selective modifying effect upon the mineral surfaces, and that any modifying effect upon the water is incidental. The modifying action of the collecting agents upon the mineral particles is sufficiently marked so that it is possible to raise larger mineral particles, and hence finer grinding becomes of less importance, or unnecessary.

The process in which organic nitrogen compounds, including azo and diazo compounds, many of which are non-frothing collecting agents, are employed, is claimed in my companion application, Serial No. 312,248 filed of even date herewith; the more specific claims of said application being directed to the process in which diazo-amino compounds are employed, and specifically to the process in which diazo-amino-toluene is employed.

The flotation process in which organic thio urea and other nitrogen-sulfur compounds, such as thio-carbanilid, many of which are likewise non-frothing collecting agents, are employed, is claimed in two joint applications, of the present applicant with Ralph Sayre Serial No. 284,981, filed March 25, 1919, and Serial No. 337,322, filed November 11, 1919.

The more comprehensive claims of the present case are intended to be of a 001m prehensive and generic character for the rocess in which such substantially nonrothing collecting agents are employed; while the specific claims of the present case are directed to the process in which diazoamino-benzene is employed.

v I claim:

1. The method of effecting the concentration of minerals by flotation, which com- .75 prises adding to the mineral pulp a small amount of a substantially non-oleaginous organic mineral collecting agent which is substantially non-frothing, and subjecting the resulting mixture to a froth flotation operation; substantially as described.

2. The method of effecting the concentration of minerals by flotation, which comprises adding to the mineral pulp a substantially non-frothing, non-oleaginous organic mlneral collecting agent which is substantially non-frothing, together with an agent having good frothing properties, and subjecting the resulting mixture to a froth flotation operation; substantially as described.

3. The methodof effecting the concentration of minerals by flotation, which comprises adding to the mineral pulp a small amount of a reduced and easily oxidizable organic mineral collecting agent which is substantially non-frothing, and subjecting the resulting mixture to a froth flotation operation; substantially as described.

4. The method of effecting the concentra- 1 tion of minerals by flotation, which comprises adding to the mineral pulp a small amount of a reduced and easily oxidizable organic mineral collecting agent which is" substantially non-frothing, together with an 1 5' agent having good frothing properties, and subjecting the resulting mixture to a froth flotation operation; substantially as described.

5. The method of effecting the concentration of minerals by flotation, which comprises adding to the mineral pulp a solution of a substantially non-frothing non-oleaginous organic collecting agent in an organic solvent therefor which has good frothing properties, and subjecting the resulting mixture to a froth flotation operation; sub stantially as described.

6. The method of effecting the concentration of minerals by flotation, which comprises adding to the mineral pulpa small amount of a reduced and readily oxidizable organic mineral collecting agent which is substantially non-frothing and which is dissolved in a solvent therefor which is a ood frothing agent, and subjecting the resullsing mixture to a froth flotation operation; substantially as described.

7. The method of effecting the concentration of minerals by flotation, which comprises adding to the mineral pulp a small-- amount of diazo-amino-benzene,. and subjctingthe resulting mixture to a froth -flotati0n operation; substantially as described. I 4 8. The method of effecting the concentrarion of minerals by flotation, Which comprises adding to the mineral pulp a small amount of Liazo-am1no-benzene, together 15 'tion of minerals by flotation, which comprises'adding to the mineral pulp a small amount of diazo-amino benzene, together with a small amount of a frothin oil, such as pine oil, and subjecting the resu ting mixture to a froth flotation operation; substantially as described.

10. The' method of effecting the concentration of minerals by flotation, which comprises adding. to the mineral pulp a small amount of diazo-amino-benzene, dissolved in anorganic solvent'therefor, and subjecting I the resulting mixture to a froth flotation operation; substantially as described.

In testimony whereof I afiix my signature.

CLEMENT L. PERKINS. 

